SVD entanglement entropy

AJ Parzygnat, T Takayanagi, Y Taki, Z Wei - Journal of High Energy …, 2023 - Springer
A bstract In this paper, we introduce a new quantity called SVD entanglement entropy. This
is a generalization of entanglement entropy in that it depends on two different states, as in …

From time-reversal symmetry to quantum Bayes' rules

AJ Parzygnat, J Fullwood - PRX Quantum, 2023 - APS
Bayes' rule, P (B| A) P (A)= P (A| B) P (B), is one of the simplest yet most profound,
ubiquitous, and far-reaching results of classical probability theory, with applications in any …

Axioms for retrodiction: achieving time-reversal symmetry with a prior

AJ Parzygnat, F Buscemi - Quantum, 2023 - quantum-journal.org
We propose a category-theoretic definition of retrodiction and use it to exhibit a time-reversal
symmetry for all quantum channels. We do this by introducing retrodiction families and …

Virtual quantum broadcasting

AJ Parzygnat, J Fullwood, F Buscemi, G Chiribella - Physical Review Letters, 2024 - APS
The quantum no-broadcasting theorem states that it is impossible to produce perfect copies
of an arbitrary quantum state, even if the copies are allowed to be correlated. Here we show …

Quantum state over time is unique

SH Lie, NHY Ng - Physical Review Research, 2024 - APS
The conventional framework of quantum theory treats space and time in vastly different ways
by representing temporal correlations via quantum channels and spatial correlations via …

Inferring the arrow of time in quantum spatiotemporal correlations

X Liu, Q Chen, O Dahlsten - Physical Review A, 2024 - APS
We consider how to tell the time-ordering associated with measurement data from quantum
experiments at two times and any number of qubits. We define an arrow of time inference …

Unification of spatiotemporal quantum formalisms: mapping between process and pseudo-density matrices via multiple-time states

X Liu, Z Jia, Y Qiu, F Li, O Dahlsten - New Journal of Physics, 2024 - iopscience.iop.org
We consider the relation between three different approaches to defining quantum states
across several times and locations: the pseudo-density matrix (PDM), the process matrix …

Quantum dynamics as a pseudo-density matrix

J Fullwood - arXiv preprint arXiv:2304.03954, 2023 - arxiv.org
While in relativity theory space evolves over time into a single entity known as spacetime,
quantum theory lacks a standard notion of how to encapsulate the dynamical evolution of a …

The Spatiotemporal Doubled‐Density Operator: A Unified Framework for Analyzing Spatial and Temporal Quantum Processes

Z Jia, D Kaszlikowski - Advanced Quantum Technologies, 2023 - Wiley Online Library
The measurement statistics for spatial and temporal quantum processes are produced
through distinct mechanisms. Measurements that are space‐like separated exhibit non …

Quantum causal inference with extremely light touch

X Liu, Y Qiu, O Dahlsten, V Vedral - arXiv preprint arXiv:2303.10544, 2023 - arxiv.org
We consider the quantum version of inferring the causal relation between events. There has
been recent progress towards identifying minimal interventions and observations needed …